Make cargo test fail more helpfully

Cargo.toml

@@ -32,6 +32,7 @@ fold = []
 clone-impls = []
 extra-traits = []
 proc-macro = ["proc-macro2/proc-macro", "quote/proc-macro"]
+test = ["syn-test-suite/all-features"]
 
 [dependencies]
 proc-macro2 = { version = "1.0.7", default-features = false }
@@ -46,6 +47,7 @@ rayon = "1.0"
 ref-cast = "1.0"
 regex = "1.0"
 reqwest = { version = "0.10", features = ["blocking"] }
+syn-test-suite = { version = "0", path = "tests/features" }
 tar = "0.4"
 termcolor = "1.0"
 walkdir = "2.1"
@@ -67,4 +69,4 @@ targets = ["x86_64-unknown-linux-gnu"]
 all-features = true
 
 [workspace]
-members = ["dev", "json"]
+members = ["dev", "json", "tests/features"]

tests/features/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "syn-test-suite"
+version = "0.0.0"
+edition = "2018"
+publish = false
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+syn-test-suite-feature-check = { path = "macro" }
+
+[features]
+all-features = ["syn-test-suite-feature-check/all-features"]

tests/features/lib.rs

@@ -0,0 +1 @@
+syn_test_suite_feature_check::check!();

tests/features/macro/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "syn-test-suite-feature-check"
+version = "0.0.0"
+edition = "2018"
+publish = false
+
+[lib]
+path = "lib.rs"
+proc-macro = true
+
+[dependencies]
+termcolor = "1.0"
+
+[features]
+all-features = []

tests/features/macro/lib.rs

@@ -0,0 +1,43 @@
+use proc_macro::TokenStream;
+use std::io::Write;
+use std::process;
+use termcolor::{Color, ColorChoice, ColorSpec, StandardStream, WriteColor};
+
+const DEBUG_NOTE: &str = ":  use --release
+  Syn's test suite has some tests that run on every source file
+  and test case in the rust-lang/rust repo, which can be pretty
+  slow in debug mode. Consider running cargo test with `--release`
+  to speed things up.";
+
+const FEATURES_ERROR: &str = ":  use --all-features
+  Syn's test suite normally only works with all-features enabled.
+  Run again with `--all-features`, or run with `--features test`
+  to bypass this check.";
+
+#[proc_macro]
+pub fn check(_input: TokenStream) -> TokenStream {
+    let ref mut stderr = StandardStream::stderr(ColorChoice::Auto);
+
+    if cfg!(debug_assertions) {
+        let yellow = ColorSpec::new().set_fg(Some(Color::Yellow)).clone();
+        let _ = writeln!(stderr);
+        let _ = stderr.set_color(yellow.clone().set_bold(true));
+        let _ = write!(stderr, "NOTE");
+        let _ = stderr.set_color(&yellow);
+        let _ = writeln!(stderr, "{}", DEBUG_NOTE);
+        let _ = stderr.reset();
+    }
+
+    if cfg!(not(feature = "all-features")) {
+        let red = ColorSpec::new().set_fg(Some(Color::Red)).clone();
+        let _ = writeln!(stderr);
+        let _ = stderr.set_color(red.clone().set_bold(true));
+        let _ = write!(stderr, "ERROR");
+        let _ = stderr.set_color(&red);
+        let _ = writeln!(stderr, "{}", FEATURES_ERROR);
+        let _ = stderr.reset();
+        process::exit(1);
+    }
+
+    TokenStream::new()
+}

tests/test_asyncness.rs

@@ -1,5 +1,3 @@
-mod features;
-
 #[macro_use]
 mod macros;
 

tests/test_attribute.rs

@@ -1,5 +1,3 @@
-mod features;
-
 #[macro_use]
 mod macros;
 

tests/test_derive_input.rs

@@ -1,5 +1,3 @@
-mod features;
-
 #[macro_use]
 mod macros;
 

tests/test_generics.rs

@@ -1,5 +1,3 @@
-mod features;
-
 #[macro_use]
 mod macros;
 

tests/test_grouping.rs

@@ -1,5 +1,3 @@
-mod features;
-
 #[macro_use]
 mod macros;
 

tests/test_ident.rs

@@ -1,5 +1,3 @@
-mod features;
-
 use proc_macro2::{Ident, Span, TokenStream};
 use std::str::FromStr;
 use syn::Result;

tests/test_iterators.rs

@@ -1,8 +1,6 @@
 use syn::punctuated::{Pair, Punctuated};
 use syn::Token;
 
-mod features;
-
 #[macro_use]
 mod macros;
 

tests/test_lit.rs

@@ -1,5 +1,3 @@
-mod features;
-
 use proc_macro2::{Span, TokenStream, TokenTree};
 use quote::ToTokens;
 use std::str::FromStr;

tests/test_meta.rs

@@ -1,5 +1,3 @@
-mod features;
-
 #[macro_use]
 mod macros;
 

tests/test_pat.rs

@@ -1,5 +1,3 @@
-mod features;
-
 use quote::quote;
 use syn::Pat;
 

tests/test_precedence.rs

@@ -18,8 +18,6 @@ extern crate rustc_ast;
 extern crate rustc_data_structures;
 extern crate rustc_span;
 
-mod features;
-
 use quote::quote;
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use regex::Regex;

tests/test_receiver.rs

@@ -1,5 +1,3 @@
-mod features;
-
 use syn::{parse_quote, FnArg, Receiver, TraitItemMethod};
 
 #[test]

tests/test_round_trip.rs

@@ -9,8 +9,6 @@ extern crate rustc_parse as parse;
 extern crate rustc_session;
 extern crate rustc_span;
 
-mod features;
-
 use quote::quote;
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use rustc_ast::ast;

tests/test_should_parse.rs

@@ -1,5 +1,3 @@
-mod features;
-
 macro_rules! should_parse {
     ($name:ident, { $($in:tt)* }) => {
         #[test]

tests/test_size.rs

@@ -1,7 +1,5 @@
 #![cfg(target_pointer_width = "64")]
 
-mod features;
-
 use std::mem;
 use syn::*;
 

tests/test_token_trees.rs

@@ -1,5 +1,3 @@
-mod features;
-
 #[macro_use]
 mod macros;
 

tests/test_visibility.rs

@@ -1,5 +1,3 @@
-mod features;
-
 use proc_macro2::TokenStream;
 use syn::parse::{Parse, ParseStream};
 use syn::{Result, Visibility};